I'd say the comment section of the website acoup.blog (which have been linked a few times on HN, that's how I discovered it), the commenters usually give the impression they've read the article. Of course it can also be due to the fact that it's a blog comment section, not those of a link-sharing site.

Slashdot is at least part of the same haplogroup, if not a close cousin.

There are some HN-alikes, such as Lobste.rs, which appears to be ~10% the size but often carries similar article selections. <https://lobste.rs/>

There is Tildes.net, which was inspired by Reddit (founder is an ex-Reddit employee). <https://tildes.net/>

There remains Metafilter, which continues to have exceptionally high S/N: <https://www.metafilter.com/>

Individual blogs and podcasts occasionally have useful discussion.

Mostly the mode seems to be waning in my experience.